In a photoresist process, which is one of the semiconductor manufacturing processes, a coating process is carried out in which a coating liquid such as a resist or the like is coated on the surface of a semiconductor wafer (hereinafter referred to as a “wafer”). For example, in a resist coating apparatus, a cup body is provided so as to surround the periphery of a spin chuck that holds a wafer. A coating liquid such as a resist liquid or the like is dropped onto the wafer on the spin chuck. The wafer is spun to form a coating film on the entire surface thereof. At this time, the coating liquid centrifugally separated from the wafer is received by the cup body and is drained from a drainage port provided under the cup body. Furthermore, the resist liquid centrifugally separated from the wafer becomes fine particles (mist). There is a possibility that the mist adheres to the wafer and contaminates the wafer. Therefore, an exhaust pipe is connected to the cup body, and the atmosphere around the wafer is exhausted to suppress contamination due to the mist. However, a solid component of the coating liquid scattered in the cup body may be scattered by the flow of an exhaust gas and may adhere to the inside of the cup body. When such a substance adheres to the inside of the cup body, problems such as fluctuation of an exhaust pressure and obstruction of drainage may occur.
In recent years, along with the high integration of a semiconductor circuit, a device having a more complicated three-dimensional structure has been studied. In the case of manufacturing such a device, from the viewpoint of increasing etching resistance, it is required to make a resist film thick, and it is necessary to use a resist liquid having a high viscosity of, for example, 200 cP or more. In such a material with high viscosity, the content of a solid component in a coating liquid is large and the solid component is easily precipitated, which requires high frequency maintenance. There is known a technique of radially supplying a solvent into a cup body together with an air flow to remove an adhered substance inside the cup body. When the solvent is supplied into the cup body, a part to which the solvent is hardly supplied may be present. This may make it difficult to sufficiently remove the adhered substance.
Since the atmosphere in the cup body is also exhausted, the adhered substance may be wound up by an exhaust gas and may enter and adhere to an exhaust path. Therefore, it is also necessary to remove an adhered substance in the exhaust path. For example, there is known a technique of providing a solvent supply nozzle in an exhaust path and removing an adhered substance flowing into and adhering to an exhaust path. However, there is a need for a technique of more efficiently removing an adhered substance.